Chapter Description

This chapter explains multiple routing protocols (particularly dynamic routing protocols) and describes their relative strengths and weaknesses. It also shows how to read a routing table easily and interpret the IPv6 routing information listed within it.

From the Book

Check Your Understanding Questions

Complete all the review questions listed here to test your understanding of the topics and concepts in this chapter. The appendix, “Answers to the ‘Check Your Understanding’ Questions,” lists the answers.

What are two advantages of static routing over dynamic routing? (Choose two.)

The configuration is less error prone.

Static routing is more secure because routers do not advertise routes.

Growing the network usually does not present a problem.

No computing overhead is involved.

The administrator has less work maintaining the configuration.

Match the description to the proper routing protocol.

Routing protocols:

RIP

IGRP

OSPF

EIGRP

BGP

Description:

Path vector exterior routing protocol:

Cisco advanced interior routing protocol:

Link-state interior routing protocol:

Distance vector interior routing protocol:

Cisco distance vector interior routing protocol:

Which statement best describes convergence on a network?

The amount of time required for routers to share administrative configuration changes, such as password changes, from one end of a network to the other end

The time required for the routers in the network to update their routing tables after a topology change has occurred

The time required for the routers in one autonomous system to learn routes to destinations in another autonomous system

The time required for routers running disparate routing protocols to update their routing tables

Dynamic routing protocols perform which two tasks? (Choose two.)

Assign IP addressing

Discover hosts

Network discovery

Propagate host default routes

Update and maintain routing tables

Which of the following parameters are used to calculate metrics? (Choose two.)

Hop count

Uptime

Bandwidth

Convergence time

Administrative distance

Which routing protocol has the most trustworthy administrative distance by default?

EIGRP internal routes

IS-IS

OSPF

RIPv1

RIPv2

Which command will show the administrative distance of routes?

show interfaces

show ip route

show ip interfaces

debug ip routing

When do directly connected networks appear in the routing table?

When they are included in a static route

When they are used as an exit interface

As soon as they are addressed and operational at Layer 2

As soon as they are addressed and operational at Layer 3

Always when a no shutdown command is issued

Router R1 is using the RIPv2 routing protocol and has discovered multiple unequal paths to reach a destination network. How will Router R1 determine which path is the best path to the destination network?

Lowest metric

Highest metric

Lowest administrative distance

Highest administrative distance

By load-balancing between up to four paths

Which of the following will trigger the sending of a link-state packet by OSPF? (Choose two.)

A change in the topology

A link to a neighbor router has become congested

The initial startup of the routing protocol process

The router update timer expiring

After examining its routing table for a best match with the destination address, which route will a router use to forward an IPv4 packet?

A level 1 child route

A level 1 parent route

A level 1 ultimate route

A level 2 supernet route

A level 2 parent route

What is different between IPv6 routing table entries and IPv4 routing table entries?

By design IPv6 is classless, so all routes are effectively level 1 ultimate routes.

Unlike IPv4, IPv6 does not use static routes to populate the routing table.

IPv6 routing tables include local route entries, which IPv4 routing tables do not.

The selection of IPv6 routes is based on the shortest matching prefix, unlike IPv4 route selection, which is based on the longest matching prefix.

Enter the proper administrative distance for each routing protocol.

eBGP:

EIGRP (Internal):

EIGRP (External):

IS-IS:

OSPF:

RIP:

Designate the following characteristics as belonging to either a classful routing protocol or a classless routing protocol.

Does not support discontiguous networks:

EIGRP, OSPF, and BGP:

Sends subnet mask information in routing updates:

Supports discontiguous networks:

RIP version 1 and IGRP:

Does not send subnet mask in its routing updates:

Allows for use of both 172.16.1.0/26 and 172.16.1.128/27 subnets in the same topology:

Explain why static routing might be preferred over dynamic routing.

What are four ways of classifying dynamic routing protocols?

What are the most common metrics used in IP dynamic routing protocols?